I continually get a sort of rash on only one arm and only on the bicep. it consists of lots of small red dots that dry up. it's only ever on one arm.

Eczema/dermatitis: A rash that is itchy and scaly is possibly eczema or ringworm (not a real worm, but a name for a fungal infection). Rashes that come and go when it is in contact with something like a watch, rubber band/hair tie, etc can be contact dermatitis, which is due to irritated skin. Eczema and dermatitis can be treated with over the counter hydrocortisone cream.