Well you're decrease in payout is expected. as the dag epoch # gets higher, your hashrate will decrease and you'll receive less shares. your mining probably wont be profitable 4-5 months from now. If you still think your shares are too low you'll have to do a google search and check other forums, im not sure how else to help you.

as for another coin to mine, I dont think there is any other coin that can give you more profit then ethereum right now