I have been getting the sensation of a pulled pec muscle on my left insertion and a spasm-like sensation in the center of my left pec as well. I only feel it if I go heavy on bench press, or if I flex my pecs by pushing my palms against my thighs. I sometimes feel it in the center of my left pec as well.
I'm pretty sure it was caused by overtraining chest. I have since been giving my pecs a rest, taking glutamine and taurine, and stretching it lightly. Since I have a bench press contest coming up in a week, I feel this sensation will psych me out and prevent me from doing well.
Go to www.elitefts site and under "Rehabilitation" in the articles section. There is a workout on shoulder/pec rehabbing that you can use for the next few days to stretch out the area. LIGHT WEIGHTS. I don't know whether a week is enough to get back to 100%. The other option is complete rest. That would psyche me out too much. I would rather use some very light weights and not feel that "pull" to help with the mental issue.....oh, ice the hell out of it ED.
I pretty much have experienced the same thing leading up to a new max or contest time.
Essentially, what you have is fatigue induced spasm in the pec, probably from repetitive Bench training. I was training 3 times a week, and would train bench about 4-6 times a week on a double day split. While the routine would increase my Bench max significantly, it seemed to a number on my pecs. An interesting note, when I was having these fatigue induced spasms, my strength did not drop at all, but it felt like my pecs were going to tear, even with the warm up weight.
What I did to combat this fatigue induced spasms yet retain my strength was to add more shoulder pressing to my routine. The pressing kept my shoulder and triceps strong and allowed my pecs to recover. I also started working in more partial bench pressing movements such as floor press, JM press, towel bench, and board press. Again, these lifts kept my shoulders and tri's strong while my pec was recovering. When the pecs were feeling more recovered, I started adding some heaving, sub-max negatives trying to use my triceps as much as possible.
All these exercises kept my nervous system fresh so that when it was time to max, my body was ready, even though I may have not benched much leading up to that max. Now that my max has moved into a region where I like it, I've reduced the number of actual "bench" workouts to the point where I'll only bench at the most twice per week, and all the other days that would have been assigned to bench pressing, I now just throw in one of the various assistive lifts, and my numbers really haven't suffered.