Tymal Mills could be forced to retire from first-class cricket after being diagnosed with a congenital back condition.

Mills, who is thought to be the fastest bowler in English cricket, moved to Sussex from Essex over the winter and has been thought of as an England bowler of the near future. But, after breaking down in the early weeks of the season, he has been diagnosed as having a narrow spinal cord, which he has been warned could, in a worst case scenario, eventually cause substantial mobility problems if he continues to bowl.

For a man with so much natural talent, who had started to find the accuracy to complement his pace, it is crushing news.

"I have accepted that I might not have a future in first-class cricket," Mills told ESPNcricinfo. "It is absolutely gutting and I had a very difficult 48 hours when I first heard the news.

"I haven't completely given up on the dream of playing Test cricket but, realistically, it looks as if my future may be in the shorter formats. I still want to play 50-over and T20 cricket."

Sussex have already announced that Mills will play no first-class cricket for a couple of months, but specialists have advised that he will probably have to limit his bowling load significantly if he is to enjoy a prolonged career.

Mills bowled in Sussex's NatWest T20 Blast victory over Gloucestershire on Sunday and took three wickets - all bowled - and could feature in the side to play Somerset on Friday. He is travelling with the squad and hopes to shake off a minor ankle injury.

With that in mind, a career as a T20 specialist seems the most likely solution for a 22-year-old who, only weeks ago, was thought of as one of the most exciting prospects in England.

"I just hope nobody portrays me as a mercenary," Mills said. "This isn't a case of me not wanting to bowl; it's a case of me having a medical condition would could affect my future. It's all been pretty hard to take."