I am sorry to hear you are worried about Indi and Amber. My name is Rebecca. I am a veterinarian and will do my best to help.
The best way to find out why they have diarrhea, and whether they have worms, would be to take a stool sample from each of them and have it checked under a microscope. If any worms or parasites (not all parasites are worms!) are seen, then you treat with the best medication for that parasite.
Panacur will help them if they have roundworms, or hookworms and may help if they have Giardia (a one celled parasite), but will not help with Coccidia, a common one celled parasite seen in kittens. Panacur will not resolve diarrhea, it is just for parasites.
Metronidazole and Albon will help with diarrhea. Albon will also treat Coccidia, metronidazole will treat Giardia. I often use metronidazole just to treat diarrhea.
If they are eating well, and not vomiting, that is good. The swollen abdomen you see could be from the stomach filling up, but could also be parasites. I would have a stool sample checked and find out if they actually have parasites, and then choose a medication for that particular parasite.
Let me know how they are doing and what else I can answer or help with. Rebecca