Off to Glasgow soon so this will be a quick response. Low sodium (salt) is also a cause of "confusion" especially if someone has poor kidney function. Given your brother has issues with kidneys I would be taking him the doctor for blood tests. All the other suggestions are good ones too, and no matter what, it needs a trip to the doctor.

Karen
Love of Life to Alex T4N2M0 SCC Tonsil, BOT, R lymph nodes
Dx March 2010 51yrs. Unresectable. HPV+ve
Tx Chemo x 3+1 cycles(cisplatin,docetaxel,5FU)- complete May 31
Chemoradiation (IMRTx35 + weekly cisplatin)
Finish Aug 27
Return to work 2 years on
3 years out Aug 27 2013 NED smile
Still underweight