He's adorable but what set up have you got the buns in? As pet shops and breeders don't recommend the right size set up/ hutch/ cage or right diet.... I learnt this the hard way and my bun suffered for it until I got help from ru
Here's a good site for rabbit care
http://www.rabbitwelfare.co.uk/ahutchisnotenough.htm
You can be an owner for years and not know these things it's not your fault it's that shops and breeders are misinformed and give you wrong info or sometimes they know and give you wrong info to get the sale so you don't realise how hard it can be