hamstring is a muscle first off.. it is is not a tendon.
unfortunately tendons and ligaments are not like muscles.. once you cause damage to them they take a long time to heal back. we see miracle stories of NFL players blow out their ACL's or MCL's and come back the next season. they have the best doctors and rehab specialists to get them back fast, however they lose a step permanently and their careers get shortened. Dan Marino for example could barely hand the ball off towards the end of his career after blowing out his ACL a few years prior.
the only drugs that can help are cortico steroids HOWEVER using them and pounding away at the injury will further cause problems. they merely shut your brain off and stop your body for inflaming the area to heal.. this gives you the false impression that you are better when you are not and continue to cause more and more damage. i had a football injury when i was in high school and the doc gave me a cortico for it, he is a scumbag and should get his head cracked open for that.. today i still suffer from the injury, had i not taken that and just let the injury heal i would of been in far better shape today.. instead i have to live with forearm issues for the rest of my life cause of that idiot doctor ... don't ever take a cortico or anti-inflammatory unless you plan on staying on for the rest of your life.
instead your best bet is acupuncture and massage therapy. i see a massage therapist every 2 weeks right at my gym and i see an acupuncturist every 2 months. and knock on wood i've been able to stay relatively healthy. listen to your body, if something hurts do not keep pounding away at it or the issue will become chronic