Tomkins was substituted in the 61st minute for fellow centre-back Scott Dann.
Speaking with Palace TV post-match, Hodgson said: "He’ll have to have a scan. He’s definitely got a hamstring problem, there’s no doubt about that, and unfortunately they normally take weeks rather than days. I’m not expecting good news but we won’t know until the scan how bad the news is. Of course it’s a shame to lose him."
You can watch post-match reaction and highlights from midnight via Palace TV. Head there by clicking here or 'Palace TV' within the app.