I am 33 year old male with a healthy physique . My height is 176 cm and weight is 76 kg. have ache in my back for last 20 days. I used to do regular exercsie . running, yoga , some stretching etc. last month I was on tour so I tried abs crunch without back support (around 50 in no. in single sitting). On 5th-6th days. my back started aching. From hip to lower back to mid back. I realized i am able to pick loads like suitcase, etc. only with some pain in my lower back. Even sneezing causes pain. The back ache persists. Also I got fever which recovered after normal medication but I lost some 3kgs in a week without exercising. I have done my x rays which also seems to be perfectly fine.