millipede medical issue..Please help

I have a giant chocolate millipede that has a large blisterlike growth on his underside(about 3/4 in. from his head). It started out small, and he would suck it in when examined, but now it is always there and over the past few months has developed two long, thick leglike protrusions. The store I bought him from told me to see a vet, but no vets in my area see millipedes. Can somebody lend me some insight on this? Thank you so much for your time.

I'm just guessing but it sounds like a parasite.

Have you tried calling your local zoo and asking them for help? They may be able to direct you to the vet that sees their animals.

No, I hadn't thought of that, but I'll try it. Thank you.