I took up running a couple of years ago and have been a fairly consistant runner ever since. Up until last month i was running fairly regularly (3-5 times a week, short runs before work, longer runs at weekends) and following a marathon training plan. I had a minor operation and stopped running for two weeks on medical advice. I started back quite carefully, going for gentle jogs and not worrying too much about timings. However, recently when i even attempt to run i get a terrible pain in my calfs. it gets so bad i have to stop and walk which aches too. what is more worrying is that it appears to be getting worse. this morning i couldn't even manage a mile before having to hobble back home. I haven't changed any of my usual warm-up practices or anything and am at a loss as to why this might be happening. I'm getting a little concerned.
In my opinion, no operation is minor, because of the effects surgery, and associated drug protocols, can have on the body that are not always foreseen. Out of curiosity, what kind of surgery, and/or drugs were used? You may be experiencing side-effects, if not complications. After all, they asked you not to run for two whole weeks