As someone who had to take 1.5 years off due to a tibial stress fracture I would either way recommend cross training in the pool as much as you can and avoid "testing" it (jumping on it, pressing it, etc). If what you are talking about is the point where the muscle meets the tibia (posterior or anterior) this is definitely a sign of a stress fracture building. It is an incredibly frustrating injury because of the nerves that also run through the area. Here is my small story..
I was ALL IN my senior year. I had an awesome summer of training and was in the best shape of my life. As the season progressed a pain developed in my tibia. I spent a lot of time on the elliptical as the season turned over into the offseason. I managed a few course records my senior year xc season but the fracture progressed further in the big meets and prevented me from running in the all state meet. I decided to pack it in and save it for my track season, where I would be able to run fast enough times to impress coaches and run in college.
My first doctor misdiagnosed (by apparently not having the aptitude to read MRI's) my tibial fracture as shin splints. I wore a boot (which I learned later did NOTHING for a tibial fracture) for 3-4 weeks and then tried to come back slowly. I went to my doctor again when the pain reoccurred and he basically did/said the same thing (a little time off, come back and try to run). The third time I went to see a new doctor (this was at the end of my indoor season and was thinking how important my spring track season would be) who immediately diagnosed the stress fracture based on the MRI I received MONTHS AGO. My spring season was over.
This fracture (posterior) finished off my high school running career and any attempt at a post-collegiate come back because I had not raced on the track since my sophomore year (Hip injury junior year, only 10:08 2-mile as a sophomore) so I had no fast track times to impress coaches. My competitive running was over.
After the dust settled and high school ended I tried a few times to come back after months and months off. Every time pain would resonate from the same spot and I shut it down. I passed my time lifting and thinking it would be okay since I wasn't going to run in college either way (I took a gap year). It got to the point where I had nothing to lose, and I started running on it 1.5 years later. I found lifting way too boring.
As I ran the pain persisted like it had in the past but I noticed it never got any worse. I ran more and more miles and it still never got worse and eventually it started GOING AWAY. Since I figured my competitive running career was over already, I kinda said "F it" and jumped into a marathon where I broke 3 and was pretty pleased with a age-division win. This was all during my freshman year of college. I continued to train and train, and still to this day my tibia HURTS TO THE TOUCH. I believe it is nerves that have yet to heal, but either way I can run on it, hard.
I am now, years later, fortunate enough to have the opportunity to run for a division one team this coming fall xc season after jumping into a race on a whim and surprising even myself (5 miler, 26:00). I now have high hopes and treat every injury like it could be my last, wisdom I would have never had without my fracture.
I hope you heal up, goodluck.