Am i overthinking this situation? I need answers :(

I’m doubting myself for whether my own dad is being really rude.

For context I recently received something I bought and was excited to share it with my mom but she was in the toilet but I couldn’t wait so I talked to her outside but it was kind of difficult to hear so I had to be louder but each word I spoke my dad would start coughing then when I waited him to clear his throat then get back to talking to my mom he started coughing again but strangely he coughs only when I’m speaking . I was really upset and confronted him but he went from ignoring me to taking his anger out on my mom and being very defensive. I genuinely don’t get what’s his problem but based of knowing him well , he usually hates whenever I buy anything with his money although it was my allowance from him.

I’m so frustrated because my mom keeps saying I’m making a big fuss over something small but it’s not only this specific situation that he has purposely interrupts me speaking then whenever I get angry he would purposely open the main door to let the public see me angry too!