ALWAYS, nurse, BEFORE solids.
Otherwise, if you nurse after solids, the baby will be too full to nurse... and it will cause a baby to 'wean' from breast.
This is per our Pediatrician.
For the 1st year of life, breastmilk/Formula is a baby's PRIMARY source of nutrition... NOT solids and NOT other liquids. And feed on-demand, for nursing. 24/7. Day and night.
Also, he may be teething. Whenever my kids were teething as babies, they would 'seem' to reject nursing.
But, your baby is nursing fine in the morning.
Also make sure, you ARE producing enough milk....
My kids as babies would also 'cluster feed'... which means a baby even needs to feed every.single.hour. They are growing...
6 months old is also a growth-spurt time... and intake needs usually increases and well as the frequency of nursings...
Feed on-demand... not on a 'schedule.'
Try offering the breast more often...
Popping on and off the breast... and only staying on for only 5 minutes... will not get him adequate intake.
Sometimes, they pop on and off the breast because output is not coming out... or they are teething, or the let down is not fast enough... like how it is in the morning.... when breasts are fuller.
Are you nursing him during the night if he wakes????
If not, then do so.
If anything, check with a Lactation Consultant... and your Pediatrician.
all the best,
Susan