Hi Harrison123. Welcome to the forum.

I am not a doctor.  However, I am a bloke and I a little bit of knowledge. 

Most lumps on the testicles are harmless. There is also a structure at the top of each testicle called the "epididymis" which might be felt as a small lump. It's possible that this is what you've found.  However, Sweetpea1980 has given you some very wise advice: see you GP to discuss the lump.  It's probably nothing, but better to be safe than sorry, and your GP might be able to give you some more helpful information about how to check your testicles and what to look out for.

i know this is almost 2 years on but i recently started checking my balls for lumps etc,

Ive felt a sensitive lump at the top of my right testicle but not on my left. I've been to doctors and they've said it's most likely just your epididymis as it's sensitive and not painful but i can't feel it on my left side.

Can the epididymis be different sizes? 

Thanks :)

I'm not a doctor but bearing in mind the poem about the old man from Devizes  :happy:, I think it's quite possible for these parts of the male anatomy to be different sizes.

I am suffering from same symptoms I think It could be Epididymitis

Epididymitis is where a tube (the epididymis) at the back of the testicles becomes swollen and painful. It's often caused by an infection and is usually treated with antibiotics.

If the testicles are also affected, it may be called epididymo-orchitis.

Check if it's epididymitis

Symptoms of epididymitis may include:

sudden or gradual pain in 1 or both of your testicles (balls)

the bag of skin containing your testicles (scrotum) feeling tender, warm and swollen

a build-up of fluid around your testicle (a hydrocele) that feels like a lump or swelling

You may have other symptoms depending on the cause, such as difficulty peeing, or a white, yellow or green discharge from the tip of the penis.

I started checking myself out too, I discovered I have this lump too on my right testicle, on the top. I cannot find it however on my left one, my researches have lead me to "epididymis" which is a natural thing? Part of our anatomy? I have been rolling both my testitcles like it shows on the guide, I can't feel any lumps or bumps on the side of any of them, just this soft lump on the top of my right testicle, when I squeeze it, it feels just like squeezing the testicle, it's tender, glad you went to the doctor, I will do that too, but I believe it's the epididymis and nothing to worry about. I watched a YouTube video that it said that it's normal to feel those lumps on the bottom or the top of a testicle, they're the epididymis. Thank you for sharing this. 

For several weeks I noticed the feeling in mine changed and one dropped and the chord became much bigger/more pronounced almost like it twisted. In the middle of the night I was rushed into hospital in agony with a massive lump on my right tescticle. They did an ultrasound and found I had a scrotal hernia, as well as something called tescticular microlithiasis. I am waiting to have an operation for the hernia, however the microlithiasis is caused by calcium deposits and needs regular monitoring because it puts you at slight increased risk of developing germ cell tescticular cancer. If you ever get severe pain in one, go to A and E immediately because it can be very serious if it is something like a torsion. Thank you all for sharing. 

For several weeks I noticed the feeling in mine changed and one dropped and the chord became much bigger/more pronounced almost like it twisted. In the middle of the night I was rushed into hospital in agony with a massive lump on my right tescticle. They did an ultrasound and found I had a scrotal hernia, as well as something called tescticular microlithiasis. I am waiting to have an operation for the hernia, however the microlithiasis is caused by calcium deposits and needs regular monitoring because it puts you at slight increased risk of developing germ cell tescticular cancer. If you ever get severe pain in one, go to A and E immediately because it can be very serious if it is something like a torsion. Thank you all for sharing.