Hello,
You can do MBA after BBA but you can't do MSc in psychology. eligibility for MSc in psychology is BSc in psychology. In Msc you will choose a specialization or a domain for that you will read/study for 2 years.
You can't go for different stream. you can appear CAT exam and do MBA and get interesting job options aboard. After MBA, you can do PhD if you want.
Hope it helps!
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