as previously mentioned, they need to see a good vet asap and will likely need to be immediately started on prescription antibiotics.
Rats are prey animals so by the time you noice they are ill, you are usually already into an emergency
As mentioned you need to beg or borrow money asap or try to make payment arrangements with your vet
there really are no other options other then vet care with a good vet experienced in treating rats (or willing to learn) and prescription meds
People with rats usually keep bank accounts with several hundred dollars for vet care (which they continually ad to) or credit cards because when they become ill, you don't have time to try to save up money