"I have been having mild fever since a couple of days thanks to the change in the weather. My doctors are not ready to let me go out lest my fever rises," he tweeted Monday. The actor will turn 90 on Dec 11, but he is not planning any big bash to celebrate the special day. The decision came following the recent death of two of his close friends, producer Yash Chopra and Shiv Sena chief Bal Thackeray. While Chopra passed away Oct 21, following dengue and subsequent multi-organ failure, Thackeray breathed his last Saturday. Dilip's wife Saira Banu found it hard to break the news of Thackeray's death to the actor as they were once very close.