I'm not a native English speaker, and I have specific concerns about the following text:
After starting my education in Veterinary Medicine and beginning to know diseases and issues that cause problems for animals and their owners, [comma] I have learned that poisoning was one of the most common problem which we had to deal with it. The interesting thing about poisoning is its diversity. It seemed surprising to me that beside of famous and notorious toxins, many essential elements and substances like Calcium, Sodium and even water can be considered toxins."
Is this correct to use a comma in this situation (for animals and their owners, I have learned...)?
Does it make sense to use surprising in this sentence? ("It seemed surprising to me that beside of famous and notorious toxins...")
Shouldn't water start with a capital letter? ("...many essential elements and substances like Calcium, Sodium and even water can be considered toxins.")