I've just been sick with the flu/high temp/ sore throat. now my mouth has swollown gums and painful white spots. what are those?

Probable yeast: If you had an antibiotic, this suggests a yeast infection of gums. You need anti yeast treatment and add a supplement of coq 10.

2 likely options: Likely its either apthous ulcers or fungal infection. Ulcers can flare up with a history such as yours and are painful but usually self limiting and resolve within 10-14 days. If fungal, you will need an anti fungal medication from your doctor. Both conditions can be addressed with different medication but a diagnosis is needed first so see a doctor. For temp relief, try orajel or ibuprofen.

Herpetic primary gin: Your first outbreak of a herpes infection manifests these symptoms. Primary herpetic gingeva stomatitis has all these classical symptoms. An anti viral med could help but most symptoms take 10 - 14 days to disappear. Feel better!