It's been 3 days and my cat hasn't pooped. And how to get rid of flea eggs on the fur

[annun]

I left my cat at the house for a day bc of an emergency (my stepdad was sent to ICU). I wasn't thinking about how hot it is these days that I only left 2 fans on and not the cooler. So when I came back it was hot like hell! It was like an oven! I saw him on the bathtub panting/dehydrated/heat stroke(?). I had to carry him out of that hot bathtub bc he wouldn't move! He was too weak to move. The bathtub was so hot. It was Sat night so I couldn't go to the vet. I gave him fresh cool water/etc. He seemed to be doing ok after. I had to leave again to see my stepdad. Then my uncle who goes to my house to check on him from time to time said he hasn't been eating his food. When I came back he was limping, always meowing at me for no apparent reason (well I couldn't understand at least), had these weird bad odor on him & always wants to lay around hiding under the bed. So I took him to the vet and to my surprised he is actually infested with a lot of fleas & running a 103.5 fever!! The Dr said he has about 1000 or more?? fleas!!! Ugh I can't believe I didn't know he had fleas. What a bad owner I am! Ugh. >.< But when the Dr checked on one of his paws and made him walk, he wasn't limping anymore. And the bad odor was gone. (Idk what that was. Fart? Or?) Dr told me to come back again in a week. So I have to clean/vaccum/etc the whole house by myself for some days now bc my mom, stepdad & bro are all in the all hospital. Anyway the vet gave him 2 Injections: Ampicillin & Gentocin. And 2 doses of Vectra cat good for 1 mo. He gave 2 doses bc my cat is big & overweight.

His fever has gone down I think. And he seems more responsive than before tho still a bit lazy. I'm not sure if that has to do with the hot weather. (It's goes to 108F+ where I live) So he drinks a lot more in one go from what I'm used to seeing but that could be bc it's so hot. And he doesn't eat very much at all. I've seen him eat only a few bites. I give him 1/4 cup of dry food & only eats a few bites. When I try putting/sprinkling some water on his dry food and put it next to him, he actually starting eating a lot more but still little. So I gave him canned food but he still only eats a tiny bit of it. And he licks his mouth a lot especially when he eats. I've never seen him do that before. And he looks at his bowl as if he wants to eat but don't & leaves. I tried putting food in front of him and he just licks it.. He'll also cry and I'll follow him to the food bowl. And he'll cry. But idk what's wrong! I saw him one time just staring at the litter box..

So 3 days later he still hasn't pooped. He pees though. What could this be? Is it constipation or something else? (I'm hoping nothing bad) With the amount of stress I'm already dealing with my family situation. It's getting a lot harder for me that my cat has fleas & won't eat much or poop. Is it time to go to the vet again? I'd hate to go the vet again bc my cat hates going there. He gets so scared & cries so much. He was there on Monday. Is this normal or should I be very concerned? My aunt told me he might be stressed out/depressed bc of what's happening in my life right now & how all my family is stressed out and the change in routine/environment. But not sure if that's the case.

Also since the Dr put Vectra on my cat. It's supposed to kill the flea adults and stop the eggs from developing. But he still has the eggs & flea dirt on his fur. How do I get rid of that? Do I have to wash him? (He hates water on him) Or does it fall on its own? Oh and he is an indoor cat that sleeps next to me on my bed sometimes & even uses my pillow.. Should I be worried that I got some of those flea eggs or something? I haven't been itching lately. I did itch on my left leg before but no idea what it was from. I guess it was fleas after all. Oh prior to all this my cat had a tick on him that my mom took out. Not sure if I should be worried if that tick has diseases or not...

Thank you very much! Sorry for the long description.