Sudden lactose intolerance as an adult?

It it suck to suddenly have lactose intolerance symptoms as an adult. 

I had vomiting and diarrhea episode last month after I drank two glasses of milk at a time. That time, I thought it could be due to the milk might expire after I opened it for three days. 

Two days ago, I consumed the same brand of milk again. One with espresso in the morning and the other one drank it just like that in the evening. Few hours later, I started to feel so bloated and gassy. I just withstood but could not sleep at night. 

The torturing night began with diarrhea twice. I thought it was over. But, the stomachache akin to Labour contraction. It did not go away even after I continued for another four diarrhea and twice vomiting. 

Those purging left me with rapid heart beats, weak legs, cold sweat and constant stomach cramp. 

I couldn't get any medicine at that state nor that I would wake husband up to get it for me. I just lied down and endured the pain until it eased when I fell asleep. 

To be honest, I thought I died when the pain stopped. Or probably it was cancer? So many wild thoughts. 

Symptoms persist the next day, but milder

When I woke up, I was worn out from the purging but still have to drive daughter to school. After that, I resumed my sleep for two hours and got ready to work. 

I was okay at the workplace but when I was back home, I had the urge to purge (I thought I was just about to let go some gas.. But its watery stool). 

I was not sure whether it was caused by the milk residue that supposed to last for 48 hours, or I had consumed some dairy products that I did not know. 

Too scared to get cappuccino with dairy milk

Though I like cappuccino so much, but the episodes of "nearly died" gastrointestinal upset made me requested plant based milk to go with my cuppa of coffee. 

It tasted bad. I am sad if I have to drink cappuccino with plant based milk for the rest of my life. Or could I develop liking on plant based coffee in future? Or should I just switch to American? 

Probably a proper diagnostic to confirm my lactose intolerance? 

Some said that when they grow older, they stop taking milk as it will cause stomach discomfort. Is it really related to aging? 

How can one, without having underlying disease, lose their lactase enzyme to digest milk? 

But I really wish that the reason behind my intolerance would be other factors such as the milk brand or contamination. I'm yet ready to give up dairy product.