Hello,

One thing I can say for sure going all out with 80% intensity during strength training sessions, 3x/week is likely to be the source of the subsequent problems that you have now incurred. There is no way that muscles recover from that intensity:
Intense exercise (weightlifting and aerobic training) causes small, micro injuries to joints, muscles and blood vessels. In response to this, the body releases “stress chemicals” to enhance the healing process.

Source: Medicine & Science in Sports & Exercise 32:317-331,2001.

The fact is, the harder you exercise, the more recovery time you need between sessions. The more often you train, the better your nutrition must be. If you really want to see results from exercise, take the time to plan your training program. A haphazard approach to diet and exercise only leads to stagnation in results and overtraining.

Additionally, there is no reason why you can't regain your flexibility without an intelligent training program.