That could be the problem right there. A BIG rule is to never house different Frog species together.

As for food, Your frog does not look majorly over weight to me. While frogs are young and growing they need to eat every day. I feed my adults every day and if they are not hungry then I take out the excess food. Some members feed them every 2/3 days as much as they can eat in 15min. Do you give them calcium supplement?

There are lots of members who own your frog species so im hoping they can help you more than I can.