For them to begin three days after an exposure is too soon for HIV symptoms
to occur and the sorts of symptoms
you describe are not typical for recntly acquired HIV either. Mouth sores, the pains you mention and increased saliva are not symptoms of HIV.
Your CBC is not markedly abnormal and is not worrisome, not for HIV or any other serious illness.
As for your specific questions:
Does this seem likely?
No, for all of the reasons I mentioned above.
What are main symptoms of Ars?