You should probably see a vet. Medicines prescribed for one animal should not be taken by another (the same as with people).
If you're in the US, you can get OTC Iver-on at Tractor Supply Stores. Mix it 1:5 Iver-on:Water and spray the whole mouse and cage/bedding/food once a week for four weeks. This cures external (fleas, mites) parasites as well as internal (worms) parasites.
Do not use ivermectin generic paste as it's mixed too unevenly for mice and has killed them in the past.
If you're in the US, Iver-on is the recommended treatment. It's also a preventative for other infestations as well. It's about $20-$30 for a small bottle. That's as cheap a medication (for the amount) that you're going to find.