Sore throat after being stung by a yellow jacket...does this mean I'm allergic?

Took my kids to the beach this past weekend and got stung by a yellow jacket. I only got stung one time luckily-they say yellow jackets will usually sting you repeatedly if you freak out, which I did. However about two hours later my throat started hurting and it got pretty bad where I couldn't sleep and it was to difficult to swallow. Does this mean that I am allergic? My mom said the same thing happened to her when she got stung by a yellow jacket once and that I should talk to the doctor about getting an epi pen in case I get stung more than once next time.