Internal problem (cf. External problem)
An internal problem is any problem that involves a conflict between Now and Next or between Oneself and Others. In general, it's better to resolve any internal problem first before any remaining external problems are addressed.
For example, consider a wife who is upset with her husband because he forgot their anniversary. This scenario includes an internal problem: she's blaming her husband and also blaming herself for blaming her husband. She likely is having both Now-Next conflicts as well as Oneself-Others conflicts. But she's also interested in having a conversation with her husband so that she can feel more cherished and adored by him; how to have this conversation is an external problem.