Last few days, my left breast, deep down inside, in the pec muscle area has been itching & appln pressure only seems to help (temp). no other symptoms?

Unusual for muscle: Itch in body. You should discuss this with your doctor to see what may be causing it that might be revealed by physical exam. Usually, itching occurs on the skin level, and not down deep into the pectoral muscle. Do get a 2nd opinion, especially if you are showing signs of hives, wheals, or swelling that will need further work up.