Is the pain sharp, dull, throbbing.....? Still present during a normal off training day? If no acute pain, discoloring or swelling in the anterior delt/pec tie in, than might suggest heat. Actual heat and cold, alternating one to the other also works well, but heat may be the first choice.
A muscle growing weaker, along with pain, may also suggest a inflamed nerve within a region. Which could be helped by a simple muscle massage from the neck down to the biceps. Or a deeper sports style massage. Though acupuncture or acupressure has worked well for many.
Some of the jocks (serious or weekend) I come in contact with rely on Excedrin for overall muscle pain. But's that's their choice, not all stomachs handle it equally well and it can be habit forming.
By all means check that problem out with a dctor, if that injury lingers.
Good Luck.