Is my kitten dying?!?

My cat has been sitting in the same spot for a few hours each day. She's usually very frisky and loves to sun bathe, but now she stays out of the sun and in her little hidey-hole. Her fur has gotten thinner over only the past 4 days! She's also been coughing and sneezing. She tries to throw up here and there, but she only succeeds sometimes. Whenever you pet her she coughs and twitches. She's very sensitive to touch now, and she can barely open her eyes all the way. I tried to get my mom to take her to the vet but she said to wait a week more or so. This has been going on for the past week, perhaps? I'm really worried and she's only 1 and a half years old. She was perfectly healthy before this. We DID put frontline on her (Stuff for ticks and fleas) and she had some sort of allergic reaction.. but this was nearly 3 weeks ago. All she did was run around the house non-stop for a few days and could never get comfortable and never could rest and sit down. Is my cat okay? Should I try to force my mom to take her to the vet again?! I'm really worried for her and I thought I was sitting with her on her last night 2 days ago.. I can't let her die at 1 and a half years old, so I don't know what I should do. I'm so afraid for her. What should I do?