Haslam, who currently sits in second spot on the World Championship standings, crashed at the fast turn three while chasing team-mate Jordi Torres during race two at Imola.
It was initially thought that Haslam had cracked a rib, but medical tests revealed that was not the case. However, the Englishman will undergo further tests as a safety precaution.
Haslam was disappointed to only walk away from Italy with a fourth-place finish as he now trails World Championship leader Jonathan Rea by 87 points after the latter secured a double victory at the Italian circuit.
"A difficult day for me," Haslam told reporters. "In Race 1 I brought home the best possible result. In Race 2 I was struggling in the braking section and I even went wide a couple of times, ending up behind [Michael] van der Mark and Jordi [Torres].
"Then I found a good pace but just as I was making up ground I had a bad highside on turn 3. I'm hurting all over now, but thinking about the crash I think I'm lucky and I should be at 100% by Donington."