Hi, I'm not sure I can offer much useful advice but I really feel for you having struggled for 18 months with my little boy who really struggles with sleep. He is still BF and sometimes feeds to sleep but does usually re-settle.
Anyway, first of all please don't think you have caused this because I am pretty sure this is not the case. I think your little one has been totally thrown off by the illness he's had and it has affected his sleep. The same thing happened to my DS who is still recovering from a 6 week long illness extravaganza! He also gets more hysterical if he's crying at night and we go in so I know what you mean by that.
It has taken me a good week, and some help from kind souls on here, to realise that my DS is overtired (he lost out on a lot of sleep over the time he was poorly). The signs for us were; 1 hour nap (at best) during the day, night terrors and night wakings and early starts (anything from 3am onward, one night it was 2am and he refused to go back down until 6!!)
So, as of last night he is on early bed time, 6pm instead of 7pm and for the first night since January he had 11.5 hours uninterrupted sleep and woke up 45 minutes LATER this morning.
I'm just sharing this with you as if you think your little boy might be overtired it could be worth a try, obviously it might be a totally different situation but the signs he is showing sound very similar to us.
Hope that helps some?