BitLocker Auto Encryption

I got an SSD installed in place of internal HDD and installed internal HDD in place of the CD Rom with help of a casing in Dell Vostro 14-3468. So when I installed win10 in my SSD and tried to access the partitions of HDD, I saw that those drives were encrypted with BitLocker. I had linked my Microsoft Account in my laptop when I had only HDD in my laptop but I did not turn BitLocker on. Now I don't have the recovery key. It is neither stored on Microsoft account. It was automatically encrypted may be due to security reasons. I am unable to boot from my HDD because it asks for BitLocker recovery key there as well (Blue colored screen). What should I do now?