jayjay

Hi, here are Jayjay from Swizerland. At last week i jumped AFF level 1 at my home dropzone. After the opening my back hurts very strongly. Outch!!!!!!! Today my back hurts strongly to and i think, this came from the opening of the parachute (280 sqft Manta)(my weight= 241 lbs). My question to the experienced jumpers & riggers are now: opens every parachute like an "Manta", or opens the Manta a little bit harder than other canopies? And what can i do to protect my back for the next time, i jumped with the Manta in the AFF course? thanks 4 answer and greetings to all yours JayJay PS:Sorry for my very bad english *gg*.