Throbbing random on and off pain right above my bicep, below my shoulder in the front. Its in one spot. Could it be muscle or vein related? No swelling

Tendinitis? . It could be tendinitis, a muscle strain, inflammation of a shoulder bursa( sac inside a joint) or bursitis. It all depends on many factors like injury, bad positioning, illness. At your age and if you don't suffer of any illnesses these are the most likely reasons. Anti- inflammatory meds as ibuprofen, ice and rest can help. If not better you would need to be seen.