My 8 week old has been breastfeed but the last month we've gradually introduced a bottle of hungry baby aptamil, he's a big hungry boy. He's now on 3 4oz bottles a day and he's been fine, no issues introducing formula. But the last 3 days he's been spitting up loads in the late afternoon until bedtime at 7. He's still happy and smiling. He had his first injections earlier in the week. Also he's on the avent 1 teats as he will eat until he's sick with breastmilk so didn't want too fast a flow.
I don't know what it is? Should I try a different formula? Or try no 2 teat? Or could he just be a little under the weather after the injections?
Any advice?