Bless you, this sounds like it's ruling your life and i bet it feels like it's not going to end!?
I felt similar as was worried about dd slipping away in her sleep as had had 4 let downs before bron came along, and couldn't bear losing another! In the end just had to take control and let myself have a life again as was going to bed when she did at 7, whilst DH was downstairs or having nights out! i would flinch at every noise she made, and was sure i was passing on my worries onto her!
Got to about 3 months and knew things had to change, so i put her down one evening and thought to myself she's ok, healthy, happy, feeding fine, clean bot, she is tired and needs to sleep like we all do... nothing bad is going to happen! Would leave her for 3 mins (a min for a every month she was), if still crying go back, put her dummy in, stroke her head, then go back out of the room, add a min to the 3 min and so on. went downstairs with my husband after putting on the monitor, and for my own peace of mind would check on her reg, then widened the gaps on checking at my own pace, but still remained firm! started to hear a difference in cry, and knew which was a distressed cry and what was just a moan. meaning i knew she could get herself back off to sleep by herself, which she did very quickly.
i know it sounds easier said than done, but maybe little one is starting to think why should i sleep, because mum seems so scared to let me, is something going to happen!?
It is scary when children get poorly, and it can disrupt routines badly, but remember, you are his mum and you know what's best for him. If it is sleep, feel positive and confident and soon enough he should follow your lead.
If this feels too much at first you can practice this during the day with their day kips, and when they start to get it give them loads of praise (you and them) when they've woken up so they feel proud that they've fallen asleep on their own!! Your confidence will grow back to where I guess it was before LO became ill.
If however you do feel like you need extra help then deffers go for it, but like the others have said don't let them make you feel like you're going mad and need pills!
my lo is now 5 months old, goes down like dream at 7, has a mini feed at about 2, then sleeps till about 6:30! We're just shattered because she's a noisy sleeper and we're ready to move back to our bedroom but feel guilty as all the advice states we have to stay in with her till she six months!
Wouldn't recommend the leaving for a few mins till they're a little older. tiny babies need a little more encouragement else just feel abandoned.