C# - Forum Tags: Can Regex Be Modified To Grab Nested Tags?

I am building a forum and I want to use forum-style tags to let the users format their posts in a limited fashion.Currently I am using Regex to do this.As per this question:How to use C# regular expressions to emulate forum tags. The problem with this,is that the regex does not distinguish between nested tags.Here is a sample of how I implemented this method:

public static string MyExtensionMethod(this string text){return TransformTags(text);}
private static string TransformTags(string input)
{string regex = @"[([^=]+)[=x22']*(S*?)['x22]*](.+?)[/(1)]";
MatchCollection matches = new Regex(regex).Matches(input);
for (int i = 0; i < matches.Count; i++)
var tag = matches[i].Groups[1].Value;
var optionalValue = matches[i].Groups[2].Value;
var content = matches[i].Groups[3].Value;
Now,if I submit something like [quote] This user posted [quote] blah [/quote] [/quote] it does not properly detect the nested quote.Instead it takes the first opening quote tag and puts it with the first closing quote tag.Do you guys recommend any solutions?Can the regex be modified to grab nested tags?Maybe I shouldn't use regex for this?