Brief Answer:
Mothercare,specialist's guidence will help.

Detailed Answer:
Hi XXXX
Thanks for the query.
Small baby is cared for/loved by every one in family.When your baby has diarhea for such a long time ,naturally you are tense. I understand your concern.
* lactose intolerance does have the loose motions But as the baby grows it may start making Lactase enzyme & the problems settles gradually, unless it is permanent intolerance-which can be familial.
* I see following possibilities in your baby-
- First time mothers are scared when their babies have loose motion. This is just due to lack of information. The babies do get loose motions in early age, till they start eating solid food. This is because ,the digestion is yet to be developed & the feeds they take are also liquid form.
If your baby has good health/standard weight for his age ( double of his birth weight at one year),If baby plays well, happy, if he is passing enough of urine daily , Does not have dehydration if the motions are not more than 4-6 times a day-please don't be much tense.it's not that problematic. you will find solution from our further discussion.
- If the motion is loose, green/red in colour,bad smelling,is accompanied by abdominal cramps it's likely that the loose motions are due to infection.
- These infections can be viral,bacterial,parasitic. Nomaly breast fed babies don't have a chance to contact infection. But as due to lactose insuffisiensy you are giving him Nestrum rice & Neogain as advised by a gastroenterologist, BUT there are chances of getting infection while preparation of food
Frequent hand cleaning( specially before preparing/feeding the baby/ the cleanliness of utensils/ water used for preparing of baby food/the water that is given to baby matter much.
Use of boiled water & clean utensils is to be adopted.
- another possible cause of infection is oral thrush. proper cleaning of baby's mouth & application of Zytee mouth paint & treatment for diarrhea with specific drug is needed in such condition.
- Third cause for infection is teething. Baby get irritated gums,tries to take any accessible thing,puts in mouth & chews it. The things carry germs if they are not properly cleaned before baby ges it.
Consultation of doctor .for specific medication is needed.

Family history of digestive problems like Celiac disease,cron's disease ,irritable bowel syndrome need to be excluded.
2.
You say he has started vomiting also recently.
_ it may be a sign of teething.
- Gastritis secondary to bowel infection.
Usually Syrup Ondem/helpsin such cases.
Apart from anti diarrhels Biochemic mixture of ferrum phos calcaria phos( 30 X) Mixed in equal proportion & given 1/6 tea spoon powder with boiled one spoon water 2-6 times according to seviarity does help.
3. In short,
You can consult a children specialist/gastroenterologist for excluding infections./need of digestive enzymes/ Ondem for vomiting/oral thrush.
Be careful while making baby food/feeding it.
Be careful about giving enough liquid to baby ( ORS ) for replacement of sodium lost , during diarrhea.
This too need confirmation from a doctor.
Ask about new feeding regime for baby.
I am sure with this information will lead you to bring your baby not only to normal but to a healthy boney baby.
wish you all the best!
I hope, the has satisfied you. Any further query is welcome.
Thank you.

---