When dealing with a headache, try boiling one cup of apple cider vinegar and one cup of water in a pot. Pour into a heat proof bowl and put on the table or other safe place that you can lean over the bowl and cover your head with a towel. Inhale the steam for a few minutes to bring some relief.
The warning on mine says not to use prior to 4 months of age. My son was in his Jolly Jumper from 3 months. The directions of use are that if they can confidently hold up their head then they are fine.
Your baby may be able to kick himself over, from his tummy to his back, as early as age 4 months. It may take him until he's about 5 or 6 months to flip from back to front, though, because he needs stronger neck and arm muscles for that maneuver. How babies learn to roll over. At about 3 months, when placed on his stomach, your baby will lift his head and shoulders high, using his arms for support. This mini-pushup helps him strengthen the muscles he'll use to roll over. He'll amaze you (and himself!) the first time he flips over.