My battery light came on while i was driving than a few minutes later everything shut off. The battery was replaced in january and alternator was replaced in october.. what could be the problem?

For the alternator to work B+ voltage must be applied to the heavier gage wire on the back of the alternator ,plus the alternator is computer controlled , by the PCM !
Charging System Indicators
BATTERY The IPC illuminates the battery indicator when the following occurs:
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The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

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The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.

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The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

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The ignition is on, with the engine off.
BATTERY NOT CHARGING The IPC illuminates the battery not charging indicator in the driver information center when the following occurs:
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The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

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The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.

Your best is to have a qualified repair shop check it out ! Could have DTC'S - diagnostic trouble codes stored !
DTC P0562
The powertrain control module (PCM) continuously monitors that the system voltage stays within the proper range. If the PCM detects an excessively high system voltage, DTC P0563 will set. A high voltage condition may cause a stalling condition or other drive ability concerns.
DTC P0621
The powertrain control module (PCM) uses the generator turn on signal circuit to control the generator. A high side driver within the PCM allows the PCM to turn the generator ON and OFF. When Generator operation is desired, the PCM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the PCM, the voltage regulator controls generator output independently of the PCM. Under certain operating conditions, the PCM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit. The PCM has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the PCM to set the DTC.
DTC P0622
Checking for codes an voltage drop testing the connections an using a scan tool to check data parameters is the only way to solve your problem . Which means taking to a qualified repair shop !