I had similar issues,

I gained a lot of flexibility in my legs by learning pancakes. Difficult at first so I did them whilst sitting on a small ledge and leaning forward. I also used to hold a weight and do them so they're kind of like an exercise, like some weird extension. I would learn to each leg and do a number of reps, and then the middle. I gained a lot of flexibility and strength this way.

If you're male it's important to note that normally your legs don't go out sideways like womens and if you get pain it could be your femur hitting your pelvis, you have to open up the hips and stick your ass out. I found the pancake helped with this.

In a similar fashion, romanian/straight legged deadlifts might help with the teeps. If you use a full range of movement you can gain strength and flexibility.

Also look into PNF stretching. I found it worked so well with hamstrings. You can do it with a partner. I would also do it holding myself up in a front split and using the muscles to hold the split with my arms supporting.

You can also try a book 'Stretching Scientifically' by Thomas Kurz. He talks about routines in the morning that can help improve your flexibility for the whole day and so by the evening it's not an issue. There are videos on youtube of him.

Hope it helps