1) Tongue burning is nearly always caused by a mild allergy. Cumin used to do it to me. Ugh.
Moms pick up new allergies (old ones get stronger) during pregnancy & postpartum. Carrying seperate DNA in our bodies mean our systems get wacky in order to allow the "invading organism" to live. Our immune & histamine responses get stomped on. When they come back online, there are often quirks (lessening or strengthening of old allergies is common).
1.5) Constant low-level allergy exposure does weird stuff to our bodies. From hayfever type symptoms (itchy, dry, or watery eyes), to digestive upsets, to skin rashes, to muscle spasms. IN THEORY, tongue/eyes/hand-foot could all be allergy related.
... People can be allergic to ANYTHING. Common ones are fairly well known, but I'm deathly allergic to watermelon. I have a friend whose skin starts bubbling and melting if they touch Teak (the wood), etc.
... Time for an "exclusion diet".
Which is a pain, but a necessity.
Instead of removing 1 food at a time (unless there is a glaring suspect)... My family removes everything except 1. Like, today we shall eat chicken. No salt/pepper/herbs/sauces. Just chicken. Tomorrow add applesauce & plain white rice.
2) Your stuff may not be related at all. Hand & foot cramps, stiffness, tightening are common... With myriad causes. From as simple as sleeping funny while cosleeping to potassium deficiencies to standing awkwardly (like with a baby on your shoulder). To hundreds of others.
3) Of course kids get dry eyes.
- Dry air
- Allergies
- Infections
- etc.