Yes, you are eligible to apply for NEET examination after qualifying class 12 with PCMB  stream from a recognised board. But, It is too late to apply for an MBBS examination, since you have been studying in completely different domain compared to  the field that you are aspiring of right now.

There is lot ofdifference between B.tech and MBBS, B.tech refers for those who has curiosity to apply the concepts and discover new one. Whereas, MBBS is something that you need to put lot of concentration right from the start.