I take these: valsartan (320 mg), amlodipine (10 mg), seroquel (100 mg), concerta (54 mg), depakote (500 mg), paxil (40mg), bupropion (300mg), and Nexium (esomeprazole) (40 mg). Can this combo cause severe low bp? Help.

It's possible. Valsartan and amlodipine are the most potent BP lowering medications on the list. One can assess the combined effects by obtaining an automatic BP machine and checking ones BP sitting and standing daily.
Possibly. Some of your medicines are specifically used to treat high bp. Sounds like your meds are working a little too well and may need your doses adjusted. But don't so this yourself. Contact your doctor .