That inflammation could be a prolapse caused by a bacterial/protozoan infection or maybe something the frog ingested (i.e. gravel). Problem we have is that since you just moved it to another tank with an Axolotl, it's hard to pinpoint the cause.
The Axolotl could be carrying a pathogen it's resistant to; but not the frog. Did you move any filter media from old tank to new one? How about gravel? If not, can presume new tank is cycling and that is not going to help issue. Would recommend adding Melafix for one week according to label instructions but have no idea if safe with Axolotl.
Also, please answer the questions below to see if we can narrow cause, thank you!
“Trouble in the Frog Enclosure”
The following information will be very helpful if provided when requesting assistance with either your frog or enclosure. To help with your questions, please utilize the below list and post the information in the proper forum area to get advice from FF members that keep the same frog. This will allow for little confusion and a faster more informed response.
1. Tank Size and volume of water in it (full, 1/2 filled, etc.)?
2. Number of inhabitants including all frogs and any fish?
3. Water source and any conditioner treatments?
4. Water Temperature and how is it heated (if so)?
5. Water chemistry levels: pH; Ammonia (NH3); Nitrites (NO2); Nitrates (NO3)? Note that if you do not have test kits, most aquariums/pet shops will do complimentary tests if you take a clean water sample.
6. Describe any filter system including model and media?[/COLOR]
7. Substrate type?
8. Tank set-up (plants (live or artificial), driftwood, hide outs and other decor? - How were things prepared prior to being put into the tank?
9. Main frog staple food and any treats? How often you feed?
10. CA, vitamins, and any other additives used (how often)?
11. Lighting set-up and hours it's used?
12. When is the last time frog ate?
13. Have you found poop lately?
14. A picture would be helpful including frog and tank (any including cell phone pics are fine).
15. How old is the frog?
16. How long have you owned him/her?
17. Is the frog wild caught or captive bred?
18. Any medications in the water (treatment dosis and for how long)?
19. Any salt in water (how much)?
20. Is the tank kept in a high or low traffic area?
21. Describe tank maintenance to include water changes, cleaning, media changes, etc.).
By Lynn(flybyferns), GrifTheGreat, and aquatic questions added by Carlos(Mentat)