Hi Tarja,
The diet is highly inappropriate for long term feeding. I believe it may play a part in his current condition. Suitable staples for axies include earthworms, axie pellets, blackworms and bloodworms. Beef liver, heart and shrimp are suitable only as occasional treats. Raw liver in particular can cause vitamin A toxicity (excessive amounts of Vit A) and malnutrition due to active enzymes. As a result, the axie's liver can get damaged (Hepatic Lipodosis/fatty liver syndrome). Liver damage in axies can cause bloat as the liver is the organ that helps in proper digestion and detoxification. I recommend the first thing you do is to change the diet. I do not recommend feeding raw livers.
It is essential to keep the water parameters and temperature optimum during this period. If you are currently fridging your axie, ensure daily 100% water changes. Do continue to offer food, particularly live blackworms during the fridging period. Judging from the photo, i would recommend you fridge your axie at least for 3 weeks and continually monitor throughout. Axies with bloat are susceptible to secondary infections so you want to ensure that he doesn't get a concurrent illness that compounds the bloat.
Fridging is the only procedure you can safely perform without veterinary attention. Hopefully your axie has a strong immunity to recover uneventfully. I do still highly recommend you bring it to a vet if possible as normally prophylactic antibiotics are warranted. If there are fluid buildup, aspirating the fluid can also help make the axie feel better as they can cause compressional discomfort to other organs.
Cheers.