This is so sad. This cat needs a vet in order to even find out what could be causing his skin disorder and shaking so that we know what she needs to hopefully recover. Based on your zip code, I was actually able to find veterinarians near you that you could call and get help for this poor stray kitty.
See the website link below.
https://www.google.com/search?ei=WTQJXLOOH47asQWLlJ6gBg&q=veterinarian%20in%20india%20784509&oq=veterinarian+in+india+784509&gs_l=psy-ab.3...12235.19296..19644...0.0..0.81.449.7......0....1..gws-wiz.......0i71j0i22i30j33i22i29i30j33i160.Hhu7P8k1-Ac&npsic=0&rflfq=1&rlha=0&rllag=26684552,92044117,13788&tbm=lcl&rldimm=9495299778648385500&ved=2ahUKEwi7tKait4vfAhUKbawKHZ7RBLgQvS4wAHoECAAQEw&rldoc=1&tbs=lrf:!2m1!1e2!3sIAE,lf:1,lf_ui:2#rlfi=hd:;si:9495299778648385500;mv:!1m2!1d26.7362521!2d92.1887713!2m2!1d26.632852399999997!2d91.8948187;tbs:lrf:!2m1!1e2!3sIAE,lf:1,lf_ui:2The skin looks like possible demodectic mites or even just a fungal infection. The skin has to be tested to determine which so that we know how to move forward. Also the cat should have baseline bloodwork done to check for any possible deficiencies or low glucose that could explain the random shaking. It likely has an eye infection if one of the eyes is closed, so that should be treated with prescription eye ointment or drops from your vet as well.
Since the cat is eating well, then there is no need to change its diet, unless of course she feels thin, then you should try feeding her kitten food to help bulk her up and provide her with more calories. It is hard to tell if she is thin based on the photos provided.
I really hope that this stray kitty is able to make a full and speedy recovery and that the resource above helps you find good quality care for her. I wish you all the best and good luck!