We went through this stage when DS was around 5 months as well, i ended up putting the night waking down to a developmental shift as he all of a sudden could do so many more things, sitting up, really paying attention to toys, grabbing, watching, etc. Once he had 'mastered' them his sleeping went back to semi-normal (1-2 times per night rather than every 2ish hours). I am not sure if solids is going to help here, but if it helps reassure you, just when i was really at breaking point it all suddenly got a whole lot better! Just be kind and gentle on yourself in the meantime and trying and try and get to bed earlier if possible, try and relax with the other stuff as well.