It’s normal for your 1.8-year-old daughter to have fine hair in those areas. It could be because her dad is hairy – sometimes it runs in the family. These hairs are not a problem and do not require any treatment. As she gets older these hairs may become thicker, but that is fine too. 

According to your symptoms, a fungal infection or an irritation might be the reason behind it. The cracked foreskin could result from either the infection or the dryness. The pinkish skin around the anal area might be related. Hygiene is the first thing that must be done to make this area stay clean and dry. Antifungal cream or simple moisturizer may be required. Keep away from strong soaps and wear loose clothes. Drink plenty of liquids and eat a balanced diet to aid the natural healing process.

You could get relieved by itching, red spots, and peeling sometimes. Switching your soap might help, but as neem doesn't work for you, let's find some alternative. Seek for soaps endowed with the elements such as tea tree or coconut oil. There is a chance that these can aid in the combat against the fungus without the risk of your skin looking dehydrated. To add, be cautious enough to rinse thoroughly and pat the skin dry after the application of the soap.

Erythrasma is an underarm infe­ction. Red or brown patches appear on the­ skin. The skin might feel itchy or uncomfortable­. A certain bacteria causes the­ infection. It thrives in warm, moist areas like­ the armpits. To treat Erythrasma, kee­p the affected are­a dry. Use antibiotic creams as directe­d. Practice good hygiene by bathing re­gularly. These steps can he­lp clear up the infection quickly and e­ffectively.

Jellyfish stings are common and can leave scars, swelling, and itching even after the pain subsides. Applying antihistamine creams can help with itching and oral antihistamines are recommended for swelling. If symptoms persist, a local methylprednisolone injection may be considered. It's best to avoid swimming and running until the scars heal to prevent further irritation.

It seems you are facing a heat rash which is a common condition. Your skin gets too hot due to the sun and it can make your skin red, itchy, and throbbing. After a time, you should avoid wearing clothes that are too tight. Make sure to wear cool, loose-fitting clothes. Moreover, always keep below clean and dry when there is a chance of heat rash. Calamine lotion can also be a good option to use to relieve the burning skin. Drinking enough water is important.