Great to hear he's almost better now
I'm sorry I can't quite remember how you 're currently getting him to sleep, or where we were before all this illness? I seem to remember you had used shh pat with some success? This would always be a good place to start, even if you have to modify it now that he's older.
Can a baby be too old for sh-pat? Are you currently feeding him to sleep mostly? It sounds like he remembers how to settle himself, if he managed ok at BT the last couple of nights - that's great
I'd continue doing that if you can, since the way they fall asleep at BT can really help set the expectations for the rest of the night. If you'd rather focus attention on naps first, then by all means continue to feed at night if you're more comfortable with that, you could also try a gentler approach to the nights if you want, if sorting out naps and routine doesn't help with the nights anyway.
Gentle Removal PlanAnother tool you could use during the day, especially if he has been able to settle himself previously (I think that's true?) is wi/wo, which can be used alongside PUPD if shh pat etc no longer works at all. Have a read of this and see what you think:
Shush-pat - How toCould you post your most recent day or two? Getting the right routine can go a long way, I know the ideal keeps changing as they grow! I'm afraid I may not be able to get on here tomorrow, working a long day, but will pop on at some point on Friday to find out how Day 1 went