Hi cmarfol,
I think getting an LC to come to your home for a consult woudl be a really good idea to get on top of any feeding issues you may be having. If he's really not keen on waking during the night, then perahps try getting more feeds in during the day. 1-2 extras might be enough to beat the 'sleepiness'. As Barb says, give him 20 mins (at most), then burp/wake and offer the other side. I'd do the same if he's chewing rather than feeding. If he's still awake and interested you can then put him back on the first side again if you want. I'd try and aim for 2-3 hourly during the day - feed before and after naps maybe.
Rashes are very common with young babies - what does it look like?
All the best