M.F.
He might be going through a growth spurt. My now two year old daughter started sleeping though the night at 2 months old. But when ever she went through a growth spurt she would wake up starving 2-3 times a night for about a week or two until my milk supply increased and she started getting more during the day. One thing I did when I realized that was happening was to try to increase the number of feedings I gave her during the day. I especially tried to squeeze in an extra one before bed. When I could do that consistently she would only wake up once a night instead of the 2-3 times until her appetite settled down.
The thing is that they go through growth spurts every 2-3 months and it can be tiring to repeat this cycle all the time. But once you start on solids it will get better. I know a lot of people have told you to start solids now. And he is 5 months old he might be ready, but let you and your pediatrician decide when that time it. But when ever you decide to start solids, please do not put water down rice cereal in a bottle and give it to your child. It is very dangerous. And one of the reasons we give rice cereal is to teach our children to eat solids the right way.
If his waking up at night is not due to hunger and just due to him wanting you. I think you've received a lot of good soothing techniques in the other posts. It was really helpful for us to send my husband in when soothing was needed rather than food, because lets face it, mom means food and it is soothing as well. I wish you the best of luck and hope he settles down soon.