Hi my son doesn't seem to eat very well he used...

Hi my son doesn't seem to eat very well he used to eat a whole jar of baby food for breakfast nibble at things all day and have a big tea now he hardly touches his food. He is going through the teething process would this be making him lose his appetite? Will he get it back? and what can i do for now? He his a breastfeed baby he will have a tit but want eat solids? Any ideas?