What Causes Pain In My Bicep?

Hi i think i slept on my arm funny last night. it's been hurting all day today. the pain is coming from just under the bicep. i think i may have had too much pressure on the artery during the night. it feels like the blood isn't flowing properly and it feels like it does if my arm is really really tired, or just had too much pressure under my arm.
This pain has happened before but only for like a second if my arms overheat.
Is there anyway to help. i've been told by friends to keep moving it and keep the blood flowing