Are these signs I need to worry about?

If it's been itching I can imagine it has been really uncomfortable to you. I know you can get over the counter cream for it so maybe it's a worth a try doing that. However, if you haven't had this seen to or checked yet by a doctor I would strongly suggest you make an appointment. Anything unusual for the first time, undiagnosed should be checked otherwise you may think it's something completely different to what the doctor says it is. As for the smell of yogurt, I can't really judge that as I haven't experienced anything like that. However, if you mean it looks like cottage cheese for example, that could be thrush which again needs to be checked. If you have spotting you need to keep an eye on that also. Hope it all gets sorted soon for you.