If I’m allergic to dairy and fish Can I eat meat?
A person that is allergic to milk essentially is allowed eat chicken until the 7th of Av, but not meat during the nine day. There are however poskim that say that this should not be taken as a blanket heter, but only if the person will feel weak by no eating chicken.
Magen Avrohom 551-28, Machtzis Hashekel ibid, Pri Megadim M:Z 551-11, M:B 551-64, Be’er Moshe 5- end of siman 88, Nitei Gavriel 38-7, R’ Y. Cahen shlit”a. M:B 551-61.