It's not just you, I run three times a week but if I tried everyday my joints wouldn't like it, rest days are my favourite days.
Well in my professional capacity as a yoga teacher I have come across a lot of people who have b*ggered themselves up with pushing on through joint pain, in running and other sporting activities.
Even 'excessive' cycling.
I've been able to help some of them, but not all.
Once cartilage is gone it's gone, although they can do marvels with keyhole surgery on some repairs.
I want and need to carry on hillwalking, cycling, running, farming, and practising / teaching Yoga for as long as possible.
So I'm afraid I'm one of those dull old 'moderation in all things' (not including moderation) type people.
My joints don’t like it either, but I am seriously stubborn and determined when it comes to a challenge.
Just keep up with the stretching then.
Sciatica is often, but not always related to tight hamstrings.
And a narrowing and or compressing of the sacro iliac joint - that can be too much sitting.. Or sitting on cr*p chairs..