Soreness/Strain Lower back & Hamstrings.

I have been a regular to the gym for the past 17 months,but last week I got a job as a fitness trainer and I only workout 2 days in this week(Monday & Wednesday),and since last Thursday or Friday I have trouble bending back and leaning over.I'll explain in detail When I bent back I feel soreness/strain/stress or whatever in my lower back just a few inches above my hips & when lean over without bending my kness the above feeling comes back this time on my hamstrings.Though i'm pretty sure it's not Pain and it's something I can't distinguish. The above mentioned feeling is comparatively lesser on my right hamstring & back. Also I find it difficult to train my back muscles only when I'm doing Bent over rows & Hyper,and no strain in doing the remaining workouts. By the way I'm just turning 23 in a few months time,just for the record. Thanks