This seems to me a classical case of what we used to call the 'scarlet fever' in olden days. It is due to type A streptococcus. So even the allopaths are quite near the diagnosis but its just not rheumatod arthritis. Nearly all the symptoms seem to fit in. The only other cause can be an allergic reaction (drug induced).
My favourites for this case would be Apis and Stramonium, in that order.

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