Aaron Carter Back Together with Melanie Martin After CPS Call

Aaron Carter is going back to square one with his baby mama -- trying to patch things up after a dramatic weekend ... which included a call to Child Protective Services.

Aaron tells TMZ ... he's back with fiancée Melanie Martin, and they're trying to work it all out for the sake of their family. He says he feels hurt by her being in contact with his estranged family, but also says everyone deserves a second chance.

You'll recall ... Aaron told us he discovered Melanie had been in touch with his sister, Angel, which he felt was a betrayal and caused them to temporarily split. He also thought she was in cahoots with his fam to try to get him under a conservatorship. He even dropped a new song about his estranged siblings called, "So much to say".

That's all water under the bridge now, it seems, but the reconciliation came with even more tension -- because we're told Aaron's fans called CPS on him after seeing Melanie put their newborn, Prince, in his bed ... which some felt was too rough for a baby.

Aaron tells us CPS came by his Lancaster, CA home to check on the baby and the general living conditions -- but found everything was in order and left without incident.