Guinea pig help

Okay so I’ve had my Guinea pigs for about 8 months now. With that being said I’m due to have my baby here in the next 7 weeks and I need help with finding a good but cheap bedding.

For my hamster I use Carefresh but I feel like that would be expensive for their decently sized cage.

I have two female pigs, both had UTI infections when I got them (didn’t know it at the time) Fortunately they both cleared up with antibiotics and haven’t had any issues since. So I’m unsure if I should be worried about choosing a bedding that could possibly irritate their girl parts.

I currently use cheap Walmart puppy pads and fleece blankets to line their cage with (I tuck the blankets into the change snaps so they can’t chew/eat them) this typically only costs me $3 every month 😂. I change the puppy pads and fleece every 3-4 days and vacuum out the poop 1-2 times a day. I just won’t want to do it while having a newborn at the same time, not only that it’s getting quite difficult to get on my hands and knees twice a day to clean, so that’s why I’m on the hunt for bedding 😂

Also how frequently do you change bedding? Do you do a half change? Full change?