"Cut" on boyfriend's toe

Dia • Healing and growing
My boyfriend and I are in a long distance relationship and I saw him this week. He told me he fell the day before on the stairs at home and he got a cut. We were in the shower together and he showed me the cut. Here's the problem;
1. The cut is on his toe at a very weird spot. Like in between his toes close to being under his foot.
2. The cut doesn't look fresh and it does not look like a cut from a fall at all. 
3. It looks very much like mild foot rot. I don't know if someone of you would know what that is. It's a fungal disease on the foot. Most of the time, it affects the crease of the toes and it creates a cut between the creases. My stepdad used to get it all the time. I had it at some point to.
4. I think he was too embarrassed to tell me exactly what it was and I understand that. I have so many ways to heal that but of course I couldn't tell him because I didn't want him to feel bad and get all awkward. 
5. He's super shy and gets embarrassed really quick so how do I bring it up without accusing him of lying and making him uncomfortable?