Is there perhaps two guinea pigs? could yours be having babies?
We used to have a cage with a wire base and let him graze in the back yard. Move the cage to a fresh site daily. we also feh him lettuce and otyher table scraps like apple cores and other pieces of fruit.
your guinea pig will require vitamin c which they get from fresh leafy greens and fresh fruit.
Do not feed your guinea pig pellets.
What should you feed your guinea pig?
Like rabbits, Guinea Pigs are herbivores and require a high fibre diet. They should have grass or grass hay (e.g. meadow, timothy, fescue, oaten, pasture, paddock or ryegrass hays) available at all times. Lucerne or clover hay can be offered but not as the sole source of fibre as they are high in calcium and protein. Suitable grasses include clover, buffalo grass, & oat grass. Guinea pigs also enjoy dandelion, milk thistle & a variety of fresh herbs.
Grass & hay encourages chewing for long periods of time and helps to keep their teeth in good condition, which grow continuously throughout the guinea pig's life. The hay is best provided to them, if possible, in a hayrack attached to their cage wall.
I'll see if i can find out how much by weight to feed. I'll be back later?