anyone have experience with this.. been doing 2x week heavy squat/leg days and after 3 weeks fear Im experiencing it :-[

If your body is telling you something is wrong then something is probably wrong. Maybe for a few weeks alternate between heavy and light. Do some speed work even inbetween a heavy week. I have been doing hamstrings twice a week and its been helping both my deadlift and squat. I've also been using Mark Bell's Hip Circle and that little thing works wonders.

I have a hard time prescribing heavy squatting/leg days to my clients and athletes 2X per week.  Body is going to experience feelings that will make you feel like you have tendonitis.  It's probably just overtraining kicking in and you need to rest or do a complete deload using 50% or less of your 1RM.  I agree with jlaplaca with the fact that with pain equals a problem, usually an imbalance that is causing this issue, so you need to heal or it help it and training probably is going to be beneficial in high intensity.

Usually it's all mobility work for a week with lower bower.  Every day I would recommend them performing SMR or simply foam rolling to all those areas affected on both legs and all surrounding tissues of the IT Band, Quads, Glutes, Hip ADD and ABDuctors to help alleviate some of the tension that is going on throughout the thigh area.  Mobility work is very dynamic, no static holding (reaching down and touching your toes, no bueno).  Alternate quads and abductor work on day #1 and then hamstrings and adductor work on day #2.  Then just alternate those two days for one week, even on your upper body lift days.  On the days your are going to do lower body, I would recommend body weight activities for just the one week to try and bring the inflammation down.  If you search the web, you can find plenty of mobility drills that can work for you for those areas.  If you are going to try them, then make sure you get the full range of motion and get good quality shortening and lengthening of the muscle while doing the work.  Make sure to foam roll everyday as stated above too either before or after you warm-up or workout for those lower body areas.  It just needs the rest and you need to work out those slight imbalances.  Good luck!!!  Any other questions please ask.

Steches various times a day help a lot with strained muscles,I stech at least 3 times daily and before and after WO, and it really helps me having full muscle motion as well as relaxing it!

Then im not part of any of these articles since i do it even before my DB and i still gained strenght and muscle mass!Streching before is what made me not gain one more injury when i started doing deadlifts again, My neck is really strainuous and without the strech routines i would have open the injury again,There are those who say strech after an exercise can actually rip the muscle but its all complete non sense to me!