Hi Worried_36.  Welcome to the forum.

It's great you've had a clear colonoscopy, but I can see how it's left you up in the air.

I am not a doctor and I have no medical qualifications, so whatever I suggest here you need to discuss with your doctor (or A doctor, if you don't trust your GP).

I suggest you need to talk your doctor about the possibility you have Irritable Bowel Syndrome (IBS).  IBS can cause all the symptoms you mention, although it doesn't explain the blood so you need to find another explanation for that.  

IBS is usually diagnosed once everything else has been eliminated. It might respond to some treatments and not others.  This means that you can't assume you don't have IBS because you don't respond to the GP's first choice of medication.

IBS is usually made worse by stress - and of course the symptoms of IBS can be very stressful themselves, making a vicious circle of worsening symptoms and increasing stress.

I've probably said too much already.  I don't know if IBS is causing your symptoms.  Time for you to return to your GP and have a discussion about where you go from here. 

Please let us know how you get on.  Your feedback helps us to improve our answers.

Please ask for Endoscopy upper  
I went for colonoscopy 3 years ago due to symptoms as yours  .. all came back ok 

now my left lymph node on neck  is swollen along with pre existing symptoms and they think it's stomach cancer . 
They need to look at top of stomach by going down throat with camera . I don't understand after doing colonoscopy 3 years ago they didn't do this then ? As I've found out that colonoscopy does lower half of tract colon and bowel , while endoscopy does stomach area etc . You mentioned heart racing .. Are you getting any heartburn or sternum pain or anything ? Hope you get answers 
I hope they listen . x 

p.s I will be suing if they find anything x