Hi I Live In Gulf. Recently I Visited India For

Hi
I live in gulf. Recently I visited india for two weeks and started chewing rajni gandha ( pan masala) there. Wheni cam back to gulf one day after i had flu cold and cough. This lasted for 4 days and my doctor treated me for viral. 5th day i had big discomfort in stomach with heavy sweating and immediately i rushed to emergency. After two days of treatment and with plain ct scan they identified infection and obstruction inthe urinary tract due to a 5 mm stone which they done a procedure to put a stent.my question is:
Cause of such illness?
Is stent completely safe?
Is temprature and little pressure feel during urine release till the time stent remains is normal
How to avoid this situation in future?
Any other advise please