Itchy

For the last few weeks on and off my inner labia and almost inside my vagina has been really itchy and almost a burning sensation, I have white discharge that is not phlem like more soft like butter , it doesn't smell bad either. I've bought some flora plus thrush gel 5 day treatment and have applied the first session tonight but I'm scared im using the wrong thing I'm 18 and don't really know what I'm doing, I'd appreciate any advice on this. Thank you x