I have 2 very small lumps less than 1cm under my skin in my forearm that are movable don't feel overly soft but not sure how squishy they should be. Gp suggested lipoma but has still referred me on an urgent referral for ultrasound to put my mind at rest. How can you determine if the lump is likely to possibly be sarcoma or just benign.

I moved squahed and played a lot last night this did irritate my skin which became red and warm is that a warning flag ?

Having had a melanona 0.5mm nearby I was concerned 

Any advice or input would be very welcomed