HELP, My 8 Month Old Is up Every Hour All of the Sudden...

It is normal for children to have irregular sleep cycles around this age, it is another one of those "milestones". He is also old enough to start to attempt the "cry it out" method.

Are you putting him in his bed after he is already asleep? Often times, babies will wake up scared not knowing how they got there and not knowing how to soothe themselves back to sleep. If you can, try laying him down in his bed while he is tired but still awake, that could help him when he starts to wake throughout the night, he will
remember his surroundings.

Since he was sick and off track, it may take him a week or so to get back in his cycle. Keeping him in bed with you will only prolong the problem.

You said he doesn't even open his eyes - could these be nightmares or night terrors, especially if he goes back to sleep quickly after being soothed. Have you tried not responding to his cries to see what happens? If he's been very sick and has been on medications, that could be messing with his body chemicals and causing the bad dreams. If he's still on meds or just recently finished them, give it some time and they should go away as his body returns to normal. Of course, you could also call his pedi and ask if this is a normal side effect of his meds and if there is something else he could be switched to.

We had the same issue and someone saved us by recommending baths before bedtime. I thought they were crazy becuase bathtime was playtime for us, but it worked the first time, no joke! She plays like crazy in the water and by the time we dry off and I lay her down to put lotion on, she's already drifting off to sleep. She's 15 months now and we have tappered back to baths every-other-night but she still sleeps through the night (we started doing it at about 7 months old).

I'm thinking nightmares or teething. My baby has nightmares sometimes. She's 15 months and sometimes she wakes up screaming and shaking. It takes her a moment to calm down, but then she passes right out again. If he's teething, you might give him some motrin and some hylands before bed and see if that helps.
Also, he might be going through a growth spurt. Is he eating well? He may be hungry.