Blacking out after a coughing fit??

[MissEmmaC]

Hello I'm asking this question on behalf of my uncle

He is a 46 year old male it stared about 3 years ago one night everyone was having afew drinks and he started to cough but he kind of passed out and fell over then it happened again afew months later but now it's nearly all the time usually if he laughs he will start to cough then his whole head goes red it's like he can't breath and sometimes he blacks out and doesn't know what's after happening until someone tell him. Last week though he told me and my family tha it happened 11 times in one day without alcohol or anything he just woke up and took the fit. And he was shaking a bit too. Then I experienced the worst one Saturday night the 13th may he went really red and wasn't really breathing then when he came around to himself he didn't know what happened but went really pale and god severe cramps in his stomach muscles. He already had chest scans and they all came back clear so what can this be it's very scary and worrying?
Can anybody help and figuring out what's causing this

Thanks emma