IgM tests are notoriously inaccurate. Since it sounds like a bit more than 2 months have passed, I'd wait another month and take a type specific IgG test to sort things out.
And your symptoms sound nothing like herpes, so my guess is the IgG will come back negative.
The ONLY tests you should trust for a conclusive diagnosis of Herpes is the IgG tests. There's one for each kind of Herpes (i.e., HSV1 and HSV2). The IgM is not a reliable test.