Please help - I am at the end of my tether 
DS1 is 2.5 years and his baby brother is 2 months old. DS1 has always been an excellent sleeper - sleeping through from about 3 months old. When DS2 was born in December it coincided with a stressful xmas and DS1 having a nasty virus (so waking in the night to cough/have medicine).
Since then our once perfect sleeper is waking in the night anything from twice to ten times (last night). He is crying in his bed or getting out of bed and walking into our room.
I am beyond shattered. I am waking to feed DS2 two or three times and then DH and I are having to wake to lead DS1 back to bed and comfort him.
We have got a gro clock which he fully understands the concept of (chatters about staying in bed until the sunshine all day) but still gets up at night. We have tried a reward chart with stickers and presents. Again he understands the concept but is still getting out of bed. We have tried reassuring him and telling him we love him (in case he is feeling insecure). DH has tried shouting at him and ordering him to stay in bed.
Nothing works. DS1 has started to go a bit longer between feeds so this really should be the start of me getting more sleep and feeling a bit more human but instead I feel worse than ever because of DS1. I am so angry with him and finding it hard to function. Plus it means that DS1 himself is tired in the day (he won't nap) so his behaviour is deteriorating.
Please- does anyone have any advice on what else we can try?