Possible grounding issue in apartment & question about showering

Hello! I'm currently renting an apartment with my roommate in a somewhat old building. Earlier today when I came back home, I loaded the washing machine and went to the kitchen to start preparing food. When I tried to use the oven, I felt a shock in the arm that was touching the oven up until my elbow. The shock was more like a very uncomfortable vibration that I felt in my muscle and lasted for as long as I was touching the oven. I turned it off immediately. After a while I tried again and the issue was still there. I googled it and I assume it's faulty grounding, I don't quite understand what that is though.

I had a similar issue a few days back in the same kitchen. I was trying to watch a video on my iPad and it was plugged on a charger. I could feel a (weaker) vibration in the palm of my hand and my fingers while I was holding it. A few months ago I felt weird tingling on my fingers when using the oven again, but it was definitely not as strong as today.

I contacted my landlord but have yet to get a response. I'm quite scared since the vibration today wasn't particularly weak or light. It was not painful but very very uncomfortable and I could feel it in my muscle.

I want to know two things:

1. A broader explanation on what is possibly happening

2. Can we use the shower? We are both students and travelling back to our hometowns for the weekend so we do need to use the shower (and the kitchen) :(

Also I know I'm basically an idiot but I truly just don't understand what's happening. Thanks!