T.B.
My youngest son was that way and we started him on a little bit of cereal in his formula at bedtime and it seemed to help him sleep during the night.
All you have to do is put about 1-2 tsp of cereal (baby cereal) any flavor in with your formula and then shake well. After you have mixed them together check to make sure it will come out of the nipple. If it does not then you need to make the hole in the nipple just a little bit bigger by putting a very small cut at the top of the nipple where the hole is. You make it just big enough for the cereal to come through.
You can start with a small amount of formula and cereal about 2 ounces and then finish with regular feeding if you would perfer.
I also gave my children mashed potatoes and butter or gravy in very small doses (1-2 tsp at a time) when we first started feeding them. Sometimes it takes them getting use to the texture and taste. You just need to keep working with them in small doses.
Don't rush him, when he is ready to eat solids he will let you know as long as there is no other reason for him not doing this.
Listen to older ladies and ask them questions as they have already dealt with most things to due with babies and are a world of information and help.
Hope this has helped you with your concerns. I have 3 kids all in their early 20s. So keep up the good work and concern for your son.