The pilot stated that he had completed several laps around the ultralight traffic pattern at Lakeland Linder Airport, when he decided to land. He entered left traffic, and while on left downwind for a landing on the ultralight runway 27, at and altitude of 400 feet AGL, he noticed another aircraft about 1,500 feet ahead of him and at a slightly lower altitude. He further stated that while turning to left base, he noticed that his airspeed was 70 mph, his altitude was 400 feet, and the airplane in front of him had slowed down considerably. When turning final, he was at an altitude of 300 ft. AGL, his airspeed was 65 MPH, and he was closing on the aircraft that was ahead him. At this point the pilot said he reduced his airspeed to just below 60 MPH. When he slowed down he noticed that the aircraft ahead of him started to increase altitude, and he was still closing on that aircraft, so the pilot said he decided to go around on the inside. He made a pretty hard bank to the left, felt the left crosswind get under his wing. His airspeed was just below 55 MPH, and he was at an altitude of 195 feet AGL, when his aircraft stalled. The pilot that as he made corrections in an attempt to recover, his aircraft abruptly turned right, causing his head to strike the canopy, and he lost consciousness. According to the pilot, that was the last thing he remembered until he awakened in the hospital the next day. The pilot said that prior to the accident there were no mechanical failures or malfunctions to his aircraft or any of its systems.