It is very hard to assess injuries like this without seeing somebody and there are so many variables. In truth you may need to enquire locally from other athletes as to who is the best physio in the area for dealing with and assessing these types of injuries. A few things you might look at however are 1. Was the injury you received to your hamstring properly worked out or is there still a ball of scar tissue there. I have found this a common cause of reinjury because with bad injuries alot of people aren't strong enough to work them out, dry needlying is not enough. 2. Are you doing alot static stretching prior to exercise, rather than warming up and doing dynamic stretching. This can prime the muscle for spasm and tears because you are overstretching the muscle and priming the stretch receptors to react and protect the muscle by causing spasm. Static stretching is the correct form of stretching after training and should be done religiously to help the muscle recover.3. Another condition players need to be on the look out for with recurrent hamstring/groin injuries etc. is ''femoral acetabular impingement'' which is basically bone impingement in the hip area which prevents the hip joint from functioning normally putting pressure on other structures. 4. Was progressive rehab strengthening program used after your hamstring injury to strengthen you and test you back to play........These are just a few things to look out for but my advice is to you is search and find a good physio early in your career, somebody also good at tissue work, somebody honest, somebody who will refer you when need be . Outside of that though grade three hamstrings are hard conditions to get right and care is needed. Best of luck, I hope I was of some help.