Different vaccine used for covid doses.

Hi, My father has taken both the doses of vaccine and when I have downloaded the vaccine certificates I found out that the first dose was of Covishield and second dose of Covaxin. Although he didn't have problem after second dose but after 10 days of second dose he fell down suddenly and was unconscious after he gained the conscious he vomitted. We reached to the doctor and he told that this is because of low BP and weakness as at that point of time his bp was 55/95. He developed fever also but lasted only for 2-3 days and doctor prescribed fever, antibiotics and mutivitamin tablets. Later on some rashes on his body.with itching. Although we didn't know that this might be because of the two different doses of vaccine as we were not aware of it at that point of time. 3 days back when I downloaded the vaccination certificate then we got to know about it. But now he is feeling much better only little bit of weakness is there. please suggest me what to do now. thanks.