Starter has lost its umpfh

My starter has stopped doubling in size. I usually feed  50g if starter with 80g strong flour, 20g wholemeal and 100g of water. Any recommendations? Should I go back to 50g starter, 50 strong flour, 50g water. 

Second question if I used rye flour to feed my starter what would the impact be to both my bread and starter?

Thanks