Hi
Very sorry to hear that you have been battling with this for such a long time. I'm only a student, so can't help you much. One thing we've learned is that the problem with hamstring injuries specifically, is that they can be painfree after about maybe 4 days without having completely healed, needing about 6 weeks or more to do so (obviously deepending on the type and severity of the injury). As a result you start putting too much stress on them too soon and they always reinjure until after 2 years scar tissue is formed. Somebody more experienced could give a more reliable and broader answer though, I'm not a physio (yet), so just commenting as a "regular" person. I don't know either if this applies to you, you don't exactly say how much rest time you have given it.