Talk to Endocrinologist on Sudden Low BP

My father is facing some issue from few days. 1st episode was on last Wednesday. At 1st we thought it was due to heat wave bcz he recovered with juices and healthy diet along with some bedrest and now again happened yesterday night when he was about to sleep. The issue is Bp low ho jta ha sir bhri pait mn dard phr sans phulti ha or vomit hoti ha phr us k foran bad shaded ghanodgi ho jati hy. Kindly guide what it could be?? does he needs any labs?? and what further investigations are needed. We are very much worried as he has his final exams of intermediate starting from Monday.