Muscle Chest Pain

After i do parallel dips or cable rear pulldowns (for lats and traps) and i extend my chest forward to stretch the pec area i feel my muscles around the chest area
hurting. I went to my GP/doctor and he told me i have inflamed muscles.

Now i have been getting this feeling for a long time(got worse as tiem passed), like 4months or so.

he said if pain persists we will investiagte further.
and he also said it could be that i might not be able to pump so much weight(genetic thing i tink)

(note the pecotralis major which is the main ches muscle)

has it happened to any of you before and does it sound liek something that could prevent me from moving forward in the competitive BBing world.