is there any simcard that I can buy in Switzerland and also use in Italy and Germany, mainly for Internet for about 15 days or 1 month maximum??
You can look into a prepaid card like NATEL easy smart. It's for sale in Swisscom shops. There is one at Zurich airport, for example. The shop staff will be able to advice you.
All you need to know about traveling by train, bus or car in Switzerland.
Hand picked Swiss hotels and other accommodations are right here.