Does anyone know why my body aches when i drink alcohol?

This last weekend I went out with a couple of friends to do a slight celebration. We were all drinking some blanco tequila (i was also drinking a white sangria) and when we were maybe i’d like to say 2 shots in I got this really bad body ache. This has happened to me before and i am quite a lightweight but i dont know why this happens to me? My back especially starts to hurt.

I drank a glass of water and sat for about 40 minutes before drinking again and I felt alright. It was probably some dehydration that time but I wonder why this happens?

Does anyone know?