Layzie Bone -- Married Rapper Has Alleged Baby Mama Drama

Trouble is brewing for Bone Thugs-N-Harmony rapper Layzie Bone ... the alleged baby mama kind.

The married father has been named in a paternity suit claiming he's the father of a one-and-a-half-year-old child ... and the mom -- not his wife -- is escalating her fight for child support.

The woman making the claim tells TMZ she followed up as recently as this week on her October filing. It's been WAY more than 30 days -- and Layzie never formally responded -- so by default the court can now declare him the father, even without a paternity test.

No comment from Layzie ... but if he thinks he can just wait this one out, bad idea ... the court charges interest on all unpaid child support installments.