I have just finished a course in Holistic Nutrition. You really shouldn't detox while nursing, but since your son is 16 months old you should be able to to make more healthy changes in your diet. You should not attempt to lose weight though. Choose fresh, whole, natural, organic (if poossible) foods. For allergies take wheat, and dairy out of your diet and his for 3 weeks and see if there is any improvement. You should see an improvement and if you do, do not add back until completely clear. Then add them back 1 at a time with a week in between to see if you can notice any reaction. You can use Millet, brown rice, amaranth, oats, or kasha instead of wheat, stay away from spelt or kamut they are related to wheat. Use Rice Dream, organic soy milk and make nut milks instead of milk, rotate them so he doesn't develop an allergie to these. One reason for allergies is constant repetition. Rotate your foods as well as his. Also give your son "Lactobacillus bifidus" it is the good bacteria, buy it in the health food store, buy one that is kept in the fridge and it wouldn't hurt for you to take some either, but it will be a different formula for an adult. Also give him 1 teaspoon of flaxseed oil, and you should take at least 2 Tablespoons. Keep flaxseed oil in the fridge. Use flaxseed oil not capsules, you can use it as salad dressing with lemon and a bit of real maple syrup, use it on veg. instead of butter, even on meat, just don't heat it. It is OK to but it on hot veg, just don't heat it.
An excellent book to read is "Super Immunity for Kids" What to feed Your Children to Keep Them Healthy Now and Prevent Disease in Their Future by Leo Galland,M.D. I learned a lot in this course, things I wish I new when my kids were small because they had diaper rashes, eczema, ear infections, and ADD. If I had to do it over I would not ever give my kids cows milk, it is meant for baby cows that are 75 lbs when born and grow up to be 1000 lbs or more. They don't drink milk for calcium, look at the size of their bones, they get their calcium from greens and grains. No other animal drinks milk after they have been weaned.