I had 6 fish. All community fish. One dies yesterday, and one died today. Now one of my other fish looks ill.?

I've had them all for 2 weeks. Got a new tank, filter..everything. Also have an albino little water frog. that i've had him for years. My fish that dies today has been swimming slower an just anging out at the bottom. Just now she dies. Now one of my fish has her eyes bulging out, one of them outlined in red, and is really fat. Thought she was pregnant, but now I think she's sick. Swimmin slower as well. Another one of my fish is now also swimming slower. Cleaned filter last night. But I don't have a lid for my tank. Could that be the problem? Or am I overfeeding them? HELP!!!