This study demonstrates simultaneous measurement of three parameters viz. refractive index of surrounding medium, temperature, and strain using etched-core fiber Bragg grating sensors. Simultaneous measurement is achieved by exciting higher order modes in the sensor using an asymmetric nonadiabatic taper and measuring difference in their Bragg wavelength shifts due to different parameters. In order to simultaneously measure three parameters, three different order modes were excited in the sensor. The ability to measure multiple parameters is useful in bio-chemical measurements as it allows us to compensate for the change in Bragg wavelength with respect to change in temperature or strain. Thus, the sensors do not need to be stabilized.