Side effect of Viagra and Cialis

I am 54 years old. Took Viagra (50mg) very good effect but, I got toxicity feeling and pain in my nerve system. I change to Cialis(10 mg) very good effect. I used it one year(once a month) littel dizzy,toxicity feeling,low blood pressure and other side effects,but okey. After a year when taking Cialis I got very dizzy, cold sweats and low blood pressure, feeling of fanting and toxcicity feeling. My dizziness lasted 3 months until it vanished.  My doctor and other doctors said It can be a Severe allergic reaction to Cialis. I start to use Cialis again. used it 3 times (in 3 months), no problem. On the 4th time taking Cialis 30 minutes after I get flashing, fever and on the 3rd day I developed cough (CT showed a big inflimation in my lung) with periodically sweat or freezing. An other patient in the hospital has almost experienced the same situation earlier (after taking Cialis). Do I have special alergi to Cialis? What can I do or what can I take with or after Cialis in case of very low blood preasure or avoiding/reducing these life threatening side effects? Is there any other medicine as good effective as Viagra or Cialis but not life threatening side effect?

AN