General Sickness:
* Masama ang pakiramdam ko. (This is the most common and general way to say "I feel sick.")
* Hindi ako maganda ang pakiramdam. (This is a more polite way to say "I don't feel well.")
* May sakit ako. (This literally means "I have a sickness." It can be used for specific illnesses, but also for general unwellness.)
More Specific:
* Nanginginig ako. (I'm shivering)
* Sumasakit ang ulo ko. (My head hurts)
* Nagsasuka ako. (I'm vomiting)
* Nilalagnat ako. (I have a fever)
You can also use verbs like masakit, nahihilo, nanghihina, etc. to describe specific symptoms.
Important Note:
Tagalog is a language with a lot of nuances. The best way to choose the right phrase is to consider the context and the severity of the illness.