That definitely sounds like teething.
The sucking motion can really hurt their gums. Have you tried rubbing teething gel on his gums a few mintue before a feed? This can help cool and ease the pain on the gums.
When my DS started teething, he went through phases where he refused a bottle point blank - I think we went for 5 days without him taking a bottle. As soon as the tooth popped through, he started taking his bottles again.
Teething can also affect their sleep.
Hugs, I know it is hard, but things will improve.
Paula