Low grade temp after vaccinations

So my daughter has a rectal temp of 37.8 so it's not quite a fever but her head is super super warm. She had her 4 month vaccines yesterday morning and we're in the middle of a heatwave here in Europe so I'm not sure if I'm being paranoid or not.

I'm a bit freaked out because my husband took the car because he's off on a stag do, so I'm alone with baby and its 3.40am and I'm worried about her. Her head is so warm to touch.

She turns 4 months on Monday. 😔

What do I do? Should I call a taxi and take her to the hospital?