Urgent help with H1-B visa

Thank you in advance for any information related to my situation.

I got a master degree in A field a couple of years ago and got a PhD degree in B field last year. My OPT for the PhD degree will be ended next month. Now I have got a job offer by using the master degree, does this mean that I can not apply for H1-B visa for the job, since my OPT is for the PhD degree? Or are there any other solutions to my situation?

Thank you again