Bleeding in 6 week 4 days. How to avoid?

Hi, my wife embryo transfer happened on 02/08. 3 embryo with 5 day blast. She tested positive in beta HCG after 16 days value 2808. After two days 6707. Doctor called for scan on 31st August. But on 29 th she had lots of bleeding (full of multiple pads) red colour and clots also came. Doctor did scan and told blood is coming from right side ovary and she could see SAC in left side with no bleeding. But she could not see fetus due to full of blood. She given progesterone injection and we repeated after 2 days also. She suggested to repeat beta HCG test. And we got value of 38000. Now flow is there for brown colour like coffee. Sometimes like coffee powder. Doctor called for scan by 05 sep again. Is there any possible for viable pregnancy? Why bleeding happened? How to avoid?