I'm not a physio but...

I had hamstring pain & tightness after cycling (I was on here a while ago). I was told by a physio to stretch & this set off a whole host of issues. Pain in medial & lateral hamstrings at knee, back pain, calf pain.

Turns out I have mega tight hip flexors that (after training my quads for the bike and a desk job) got worse. Stretching the hamstrings 1) made the tightness & hip imbalance worse and 2) injured them to the point of tendonitis.

It's just now that I'm aggressively stretching/rolling quads, lower back and hip flexors that 3-4 months of intractable hamstring pain is easing off (in the space of about 2 weeks). But now I'm stuck with a difficult adductor/medial hamstring tendon issue that may take months to resolve.

Be very careful & I would echo the advice on here to seek another opinion of the advice of one physio doesn't help.