Girls, I urgently need your advice on what to do. My baby is 7 months …

Girls, I urgently need your advice on what to do. My baby is 7 months old, she has teething, naturally there's a fever, and she constantly wants to breastfeed. Also, I'm pregnant at 14 weeks and losing weight very quickly. Naturally, the second baby in my belly also suffers, doctors said to stop breastfeeding immediately, but I don't know how. She needs to breastfeed now because of her illness, she can't sleep without it at night, and the second baby also suffers from lack of milk, what should I do? Please help!