Need help, please help :/

My cat has a problem with her teeth, they are falling out and the cat has the black spots on her gums..she also has awfull breath and did also lost weight enormously in last few months. She drinks a lot of wather, puking some times and urinating guite often and she is tired most of the time.. She is only 3,5 years old. And the other cat which I have is starting to show similar sings like teeth falling out, bad breath, throwing up some times.. but she has no problem with her weight. She is pretty fat actually and about a year younger from the older one.. so what do you think I should do? I know the first suggestion is take them to veterinarian, but here's the thing, I really dont have money cuz I'm a student living on my own without any scollarship or parrenting money, and just basic examination of the cat costs about 40€, and I have 2 cats. Where are then all the secondary examinations and possible treats/pills/medications..however..can I do something without veterinarian's help?? Maybe buy some medicine or special kind of food or anything? Please help!!

P.s. Really sorry for my english xD