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The load current from a DC motor probably is random ! It depends on the mechanical motor load, friction, inductance of the motor windings and commutator position.
The only way to get an AVERAGE reading is to use an averaging filter. You can do this in software by taking many readings and mathematically finding their mean or you can use an RC filter to average the voltage itself.
You are using very high gain in the amplifier which is not helping the situation.
Be careful with your circuit, if you are using positive and negative supplies to the op-amp you should protect the PIC from possible negative voltages at its ADC pin.