No periods for 3 months/pregnancy. Do?

My sister name is Sanvi, 37years, always have irregular period issue. From last 3 months she didn't get period. So after 1 n half month,she check the pregnancy strip which was negative. Once again on 3rd March,she checked it, this time also it was negative. So she went to gynac. The doctor suggested Thyroid test n sonogrphy. Which show that increase in the value of Tsh n small hemorrhagic cyst in right overy, n bulky right overy. She already have thyroid so she improve the power of tablets and prescribed deviry 10mg for 3 days 3 times for period purpose. But after 10 days stopped tablet she didn't get period, so again she went to doctor then she gave her aqsusten 25 mg injection. But still she didn't get period. So after 7 days, once again she went to gynac. On 25.3.19 she again done upt checked which show positive. Doctor said she is pregnant but now what to do? Is it safe to continue pregency after taking deviry n aqsustan injection. N what about the cyst. Please guide what to do?